RESUMEN
OBJECTIVE: The aim of the study was to determine the effectiveness of the lateral approach to subacromial injection, compared with the posterior approach, for the treatment of subacromial impingement syndrome. METHOD: A pragmatic randomized controlled trial was carried out in an outpatient community musculoskeletal service. The sample comprised 80 adults, aged 18 years or over, with subacromial impingement syndrome. The intervention group received a single subacromial injection, using a 21-gauge green needle, of 40 mg/ml triamcinolone acetonide (Kenalog) and 4 ml 1% lignocaine using a lateral approach. The control group received identical treatment, with the exception that the injection was given using a posterior approach. The outcome measures were pain measured using 0-10 numerical pain scale and shoulder pain and disability index (SPADI) scores at 8 and 12 weeks' follow-up. RESULT: A moderate but statistically and clinically significant difference in improvement in daytime pain (mean change in score) occurred in favour of the lateral group (mean = 4.0) compared with the posterior group (mean = 2.0) between weeks 0 and 8 (1.4 points [95% confidence interval 0.3, 2.6; p = 0.018]). However, there were no statistically significant differences between the groups in night-time pain, shoulder function and SPADI scores. There was a statistically and clinically significant difference (p = 0.001) within the groups for all clinical outcomes between weeks 0 and 8, and between weeks 0 and 12. CONCLUSION: There were no significant differences in the treatments; however, both forms of treatment were associated with a significant improvement in shoulder pain, function and disability.